Greetings...I think I've found a problem with your plugin since the WP 3.5 update....
Doesn't happen all the time....but if I activate your plugin and open or manipulate the widget tiny mce text area in any way the main post and page visual editor in WP locks into a height of 5000px and whatever is remebering my height adjustment, I must imagine a cookie...does not store my selected height value for the visual editor window.
I know you took pains to update your plugin to meet the new 3.5 update of tinymce...but I may have uncovered another issue...it's hard to repeat...but pretty sure if I decativeate your plugin my problems go away and if I activate it and then edit the content of any instances of your widget, my main visual editor resizes height to 5000px and then won't remember any resizes.
any help is much appreciated!
Kind Regards, Fred Shequine